1. Technical Field
The present invention relates to an image processing apparatus, an image display apparatus, and an image processing method.
2. Related Art
In the case where an image display apparatus such as a projector displays an image, image processing such as scaling and image quality improvement processing is executed to an inputted image signal and an image in the state where the execution of the image processing is executed is displayed. However, in general, the image display apparatus does not determine whether the inputted image signal is an image signal that is up-converted or a high-definition (HD) signal (Hi-Vision video signal) that is not up-converted. Therefore, for example, in the case where an image signal of 1080 p is inputted, the image display apparatus executes image processing irrespective of the resolution of the original image expressed by this image signal and therefore appropriate image processing cannot be executed in some cases.
Specifically, for example, in the case of an image signal of 1080 p inputted to the image display apparatus, this image signal may be an image signal that is up-converted from an image signal of 480 p, or may be an HD signal that is not up-converted. For an up-converted image signal, its original image generally has low resolution and lacks high-frequency components. Therefore, when the image display apparatus executes image processing corresponding to the HD signal, appropriate effects cannot be achieved. Meanwhile, when the image display apparatus executes image processing corresponding to a standard-definition (SD) signal (standard video signal), appropriate effects cannot be achieved if the actual image signal is an HD signal.
For example, JP-A-2009-15025 describes a technique in which, based on the data volume after executing high-pass filter processing to image data of plural image frames, it is determined whether or not the plural image frames are image frames converted from image frames having a second number of pixels that is smaller than a first number of pixels.
However, in the technique described in JP-A-2009-15025, high-pass filter processing in the horizontal and the vertical directions to the image data of the plural image frames, enlargement rate determination processing in the horizontal direction and the vertical direction, and overall determination processing are executed. Therefore, it takes time to acquire the results of the determinations. Moreover, in this technique, no feedback control is carried out and therefore sufficient effects may not be achieved even if image processing is executed according to the results of the determinations.